Validation of New sEMG Electrode Placement Guidelines for the Triceps Surae in Post-stroke Individuals

Background and rationale: Surface electromyography (EMG) is a non-invasive method to measure muscle activity, among others in people after a stroke during gait analysis. Measurement quality is strongly influenced by electrode placement. However, the commonly used SENIAM guidelines do not take individual variations in muscle morphology into account, which can lead to inaccurate measurements. In previous research demonstrated that the standard placement on the triceps surae (medial and lateral gastrocnemius and soleus) was suboptimal at the group level and sometimes even problematic at the individual level. Therefore, new placement guidelines (EPICA guidelines, Electrode Placement for Individual Calf Anatomy) were developed, which are currently being tested in healthy individuals. Method: In this project aims to validate these newly developed guidelines in people after a stroke who exhibit atrophy of their calf muscles. For each participant, electrode positions on the hemiplegic side will be determined according to our guidelines while the participant is lying prone. Circular stickers will be used instead of actual EMG electrodes and will be placed according to the EPICA guidelines as well as according to the SENIAM guidelines. Subsequently, the muscle borders of the triceps surae will be identified on the participant's leg using 2D ultrasound. Afterwards, the distance between the electrodes and the surrounding muscle borders will be measured to map electrode placement on the muscle in order to validate the guidelines. In the second part of this study, 3D ultrasound recordings will be made of the soleus, medial gastrocnemius, and lateral gastrocnemius with the electrodes (stickers) on these muscles, so that during image processing, electrode positions can be visualized relative to the entire muscle, including along the depth axis. In addition, participants who can safely walk without an ankle-foot orthosis will be asked to walk a maximum of five times ten meters.